It is possible to leverage the technique on page10 to make more than two columns. The nuclear family always makes two columns. But if its floated child is a nuclear family itself, then we have a way of making a third column. Here is a simple example, it takes the nuclear family of Fig 1. on page 10 as the floated child of a new nuclear family, one whose pink background will form a third column:
Fig 2.
<div class="nuclear" style="width: 602px; background: #fcc; padding-left: 10px;">
<div style="float: right; width: 401px; background: #ffc; padding-left: 10px; border-left: 1px solid #000;">
<div style="float:right; width: 200px; border-left: 1px solid #000; background: #cfc;">
This column is floated right in the parent of the nuclear family that forms the yellow and green ...</div>
You are seeing the yellow background of the parent of ... the yellow and green ... </div>
Here you are seeing the pink background of the parent of the top wrapper
</div>
You can go on to produce more columns by making the parent of the above the child of the next super parent.
We have noted the limitation of this general idea on page 10. You need to know which is the longest column of each nuclear family. There are various ways of organising such columns so that the longest does not have to be on the end. But enough on this. You go play with it!